/**
 *    Copyright 2009-2021 the original author or authors.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package org.apache.ibatis.mapping;

/**
 * Represents the content of a mapped statement read from an XML file or an annotation.
 * It creates the SQL that will be passed to the database out of the input parameter received from the user.
 *
 * @author Clinton Begin
 *
 * SqlSource的四种实现
 * - DynamicSqlSource：动态SQL语句，所谓动态SQL语句就是含有动态SQL的语句或者含有占位符${}的语句
 * - RawSqlSource：原生SQL语句 指的是非动态SQL语句，语句中可能含有 #{} 的语句，但是不包含动态SQL的语句
 * - StaticSqlSource：静态语句 语句中可能有 ? 可以直接交给数据库执行
 * - ProviderSqlSource：上面的都是通过XML文件获取的SQL，ProviderSqlSource是从注解获取的SQL语句
 *
 * - DynamicSqlSource 和 RawSqlSource 都会被处理成 StaticSqlSource
 */
public interface SqlSource {

  /**
   * 获取一个 BoundSql对象
   * @param parameterObject 参数对象
   * @return BoundSql对象
   */
  BoundSql getBoundSql(Object parameterObject);

}
